The invention relates to a power line communication (PLC) system comprising                a power supply circuit comprising                    a number N, N≧2, of cyclically switched electronic converters connected in parallel and having respective outputs connected to a common output terminal of the power supply circuit; and            a controller providing switching pulse signals for switching the converters with a switching frequency that is the same for all converters;                        at least one load circuit connected to the output terminal of the power supply circuit;        a PLC transmitter arranged to modulate an output current from the output terminal of the power supply circuit; and        a PLC receiver in said at least one load circuit.        
In a power line communication (PLC) system, a power line that connects an electric power source to a consumer is used for transmitting signals in addition to the electric power, for example for the purpose of remote control of the consumer. Power line communication eliminates the need to install specific communication wirelines and nevertheless avoids the costs for wireless communication equipment.
Typically, the transmitter modulates the voltage or current on the power line with a switching frequency f0 that is significantly higher than the grid frequency of 50 or 60 Hz, so that the communication signals can readily be separated from the grid frequency in case of an AC power supply.
In addition to broadcasting messages to all receivers that are connected to the power supply circuit, it is also possible to address individual receivers. In order to limit the bandwidth requirements and to be able to use identical receivers in the different load circuits, a communication protocol may be used in which each message is accompanied by an address sequence that identifies the individual receiver for which the message was intended. In this case, a commissioning procedure is performed in order to assign a specific address to each receiver.
A general problem in conjunction with power line communication is to control the range of the communication signals such that, on the one hand, all connected receivers can safely receive the messages with a sufficient signal to noise ratio and, on the other hand, the signals are not spread so far over the power grid that privacy of the communication is compromised.